| In compression wood the tracheid becomes quite round in cross section, forming intercellular spaces between neighbouring tracheids. |
| Little or no plastic deformation is seen in tracheid walls in ring 26, which is the last ring formed in the tree. |
| As the tracheid cytoplasm undergoes autolysis, the matrix materials in pit membranes of Metasequoia are removed from both torus and margo regions. |
| As a rule buckling of a tracheid begins at the bordered pits which form places of least resistance in the walls. |
| Water moving from tracheid to tracheid must pass through a thin modified primary cell wall known as the pit membrane, which serves to prevent the passage of damaging air bubbles. |
| If trees pull water, that in the xylem would have to be held on the tracheid and vessel walls by adhesion, and water molecules would have to hold together by cohesion. |
